Let me start with a confession: I tend to treat "stupid" people I interact with badly, if I run into their intellectual limitations. And that's even though I am fully aware that not being intelligent does not make you a bad person, and that that feature is not something people chose for themselves. My gut reaction is that if they don't get it (no matter what "it" is), they must be failing to pay attention, so I get testy (and that's not very smart of me, no matter the cognitive ability present).
This reaction is due partially to myself living in a real-life filter bubble; I've studied physics and worked in server IT since. The people I really interact with tend to be in the top 5% regarding intelligence, and my idea of what "normal" looks like therefore is seriously skewed.
Something that has annoyed me for a long time now was men in a computing context treating me as a moron until I had figuratively hit them over the head a few times, and some even needing occasional reminders. "Women are either stupid or crazy, or both" is a sentiment I have heard all too often. The angry if uncharitable reply to that is that what they really said was that no sane and smart woman would stand their company long enough so they could get to know her.
Lately I have been considering the possibility that those men who believe that men are so much smarter than women (even if they have learned to not say that aloud, many show it in their behavior) aren't actually speaking and acting from their experience, and if the angry retort was possibly literally true: They start out in a field with few enough women that they meet no woman peers, and the only women they interact with are in crappy "supportive" jobs that aren't paid enough, nor interesting enough, to attract women who can do better. The afflicted men then either really don't go out much or act towards women in a manner that is repulsive to people with an IQ above room temperature, which keeps intelligent women who have any self-respect away from them and thus reinforces their belief that women as a class were stupid, or basket cases.
What do you think? Is the high number of otherwise fairly smart men in IT who are decidedly sexist a result of a self-reinforcing real-life filter bubble? Or do you have a better theory?